It is common to utilize radio frequency (RF) signals, having particular characteristics, in conducting information communication such as voice and data communication. For example, wireless communications, including cellular, global system for mobile (GSM) and personal communication services (PCS), utilize RF signals of predefined frequencies of particular bandwidths, in order to transmit information between two communication nodes.
Multiple schemes have been developed to conduct a plurality of simultaneous communications without substantial interference there between. For example, frequency division has been utilized to divide available spectrum into channels assignable to particular ones of the communication nodes in order to provide for their intercommunication, such as is used in the Advance Mobile Phone Service (AMPS) and narrowband AMPS (N-AMPS). Likewise, code division multiple access (CDMA) has been utilized, such as provided for in Interim Standard 95 (IS-95), to assign chip codes to particular ones of the communication nodes in order to provide for their intercommunication over a broadband carrier simultaneously utilized by other ones of the communication nodes. Similarly, time division multiple access (TDMA) schemes have been utilized, such as provided for under the United States Digital Cellular System (USDC) standard IS-54, to distribute time bursts of available communication capacity among communication nodes. Additionally, in establishing a wireless communication infrastructure providing for multiple service providers, portions of available spectrum in the United States have been established to allow provision of wireless communication services, regardless of the particular scheme utilized for providing the communications, i.e., "A band" service provider and "B band" service provider in the same geographic area.
In providing the above described communications, it is often necessary to manipulate signals as they pass through, or are otherwise handled by, the communication system in order that they may be utilized in a desired manner. Typically in wireless communication systems, as well as other systems, signal amplification is necessary in order to provide a signal which exhibits proper characteristics, such as is provided to a receiving communication node with a desired signal magnitude or signal to noise (S/N) ratio. However, in order to provide a desired amplified signal without introducing distortion or other undesired characteristics it is often necessary to utilize costly equipment such as linear power amplifiers (LPA). Moreover, as such communications may include multiple nodes operating within a same area, although upon different assigned channels i.e., multiple subscriber units operating within a single sector of a cellular communication system cell, signal amplification associated with a particular antenna, or other common signal path, must provide linearity throughout a wide range of frequencies, further necessitating the use of costly equipment.
Accordingly, solutions in the past have included the disposing of various forms of LPAs in the signal paths of RF communication signals. For example, feed forward LPA amplifier technology has been utilized, although such technology is relatively expensive as typical feed-forward LPAs use internally generated pilot tones to assist in the adjustment of internal settings necessary for the linearization of multiple carrier or complex waveform signals. Moreover, where multiple LPAs are required, such as in a distributed amplifier configuration or where multiple antenna beams each have associated therewith a LPA, the replication of the above internal circuitry, and therefore its added expense, is required for each amplifier.
Therefore, a need exists in the art for a system and method for providing a signal in a desired condition without introducing distortion or other undesired characteristics through its manipulation. There is a further need in the art for the provision of the signal in a desired condition through the use of less complicated and less costly equipment. Moreover, there is a need in the art for providing such signals in the desired condition irrespective of the scheme, or schemes, utilized to allow multiple simultaneous communications.